The consumption of bottled drinking water has increased considerably in the recent years. The main objective of this study was to investigate the changes of total organic carbon (TOC) level in bottled water under various environmental stress conditions. In this study, samples of drinking water were taken just before and after bottling process from three mineral water bottling plants in Tehran province, and the comparison of the levels of TOC content of the water was evaluated before and after bottling process, and at the end of the consumption period. The results indicate that TOC level in mineral water increases over time. There were very few changes of TOC level in the bottled water after one day. After one month and then three months, the changes became more significant in a way that the TOC level increased from 1.6 to 2.33 mg/L. Studying the bottled waters just few days left to their expiration dates revealed that the level of TOC increased twice, i.e. from 1.6 to 2.9 mg/L. Also, the level of TOC in samples changed significantly one month after the expiration date, and it increased from the initial 1.6 to 3.2mg/L. The level of TOC in samples exposed to sun was almost four times more, and reached its highest level of 5.47 mg/L. Also, the level of changes in samples after freezing increased from initial 1.6 to 4.11 mg/L.